It has become well established that there are major health benefits from regular endoscopic examinations of a patient's internal structures such as the alimentary canals and airways, e.g., the esophagus, stomach, lungs, colon, uterus, urethra, kidney, and other organ systems. Endoscopes are also commonly used to perform surgical, therapeutic, diagnostic or other medical procedures under direct visualization. A conventional imaging endoscope used for such procedures generally includes an illuminating mechanism such as a fiber optic light guide connected to a proximal source of light, and an imaging means such as an imaging light guide to carry an image to a remote camera or eye piece or a miniature video camera within the endoscope itself. In addition, most endoscopes include one or more working channels through which medical devices such as biopsy forceps, snares, fulguration probes and other tools may be passed in order to perform a procedure at a desired location in the patient's body.
In connection with the endoscope, an operator handle is typically provided that allows a user to steer and control the operation of the endoscope. The endoscope is guided through the patient's tract or canal until an opening such as an imaging port at the distal end of the endoscope is proximate to the area of the patient's body which is to be examined or receive treatment. At this point, the endoscope allows other components, such as a catheter, to access the targeted area.
In many endoscopic procedures, the physician or operator needs to rotate an endoscope shaft in order to obtain the desired images, to obtain a desired position of the distal tip, or to perform a desired surgical function (e.g. polyp removal, drainage, and the like). An endoscope shaft with torque transfer characteristics facilitates shaft rotation in the patient's anatomy by allowing the shaft to twist around its central axis. Excessive rotation of the shaft can damage the cables, tubes and electrical wires within the device. On the other hand, an endoscope shaft that is not allowed to rotate relative to the position of the handle at all may loop over itself during clinical use, causing damage to the internal components as well as discomfort to the patient. In a traditional endoscope system, when loops build up in the shaft, the physician typically propagates the loops back into the proximal portion of the shaft to keep the loops out of the physician's way. However, the loops can shorten the proximal shaft. In some cases when there is an excessive amount of looping in the shaft, the physician is forced to disconnect the scope from a console, untwist the proximal shaft, and reconnect the scope.
Low cost, disposable medical devices designated for a single use have become popular for instruments that are difficult to sterilize or clean properly. Single-use, disposable devices are packaged in sterile wrappers to avoid the risk of pathogenic cross-contamination of diseases such as HIV, hepatitis, and other pathogens. Hospitals generally welcome the convenience of single-use disposable products because they no longer have to be concerned with product age, overuse, breakage, malfunction and sterilization. One medical device that has not previously been inexpensive enough to be considered truly disposable is the endoscope, such as a colonoscope, ureteroscope, gastroscope, bronchoscope, duodenoscope, etc. Such a single-use or disposable endoscope is described in U.S. patent application Ser. No. 10/406,149, filed Apr. 1, 2003, and in a U.S. continuation-in-part patent application Ser. No. 10/811,781, filed Mar. 29, 2004, and in a U.S. continuation-in-part patent application Ser. No. 10/956,007, filed Sep. 30, 2004, that are assigned to Scimed Life Systems, Inc., now Boston Scientific Scimed, Inc. and are herein incorporated by reference. In some single-use or disposable medical device systems, the system is configured to reject a medical device that has been previously used. Therefore, when a physician builds up loops in the proximal shaft of a single-use device in such a system, the physician is not able to disconnect and reconnect the shaft to remove the loops. In such a situation, the physician is left with the option of using the device with a shorter working length.